1. Field of the Invention
The present invention relates to a fastener with tape such as a snap fastener or an eyelet, and more specifically to a fastener with tape in which a plurality of fastening members or the like made of synthetic resin are mounted integrally on the same tape.
2. Description of the Related Art
This kind of fastener with tape has at least one mounting hole on a single tape, in which an eyelet or a male or female fastening member of a snap fastener, or other kind of fastening member, which is made of synthetic resin and has a desired conFIGuration, is molded integrally on front and rear surfaces of the tape so as to enclose an entire periphery of the mounting hole.
The method for producing such a fastener is disclosed in, for example, U.S. Pat. No. 2,821,764 and EP Patent No. 0228293. Further, the applicant of this patent application has already proposed such a fastener in Japanese Patent Application No. 10-138722 now copending U.S. application Ser. No. 09/306,168, filed May 6, 1999. The aforementioned U.S. Pat. No. 2,821,764 discloses that, for forming mounting holes on a sheet-like material and then molding an eyelet of synthetic resin having a desired shape on front and rear surfaces of the tape so as to hold an entire periphery of each mounting hole, each mounting-hole peripheral portions of the sheet-like material extending around the mounting hole is clamped and held at plural positions by plural pairs of pin members which protrude into a cavity for molding the eyelet, and then molten resin is introduced into the cavity so as to mold the eyelet of synthetic resin integrally onto the sheet-like material.
Generally, if no pin members are used in the molding, the mounting-hole peripheral portion of the sheet-like material extending in the cavity would be largely waved in a circumferential direction by an introduction pressure of molten resin. Therefore, at worst, a part of the peripheral portion is deflected to make contact with an inner face of the cavity, in which case the sheet-like material may be exposed from a part of a surface of the eyelet as a final product. The invention of the aforementioned US patent pays attention to the fact that appropriate waving of the mounting-hole peripheral portion of the sheet-like material induces an increase of fixing strength of the eyelet to the sheet-like material. To achieve such appropriate waving, the mounting-hole peripheral portion of the sheet-like material is clamped and held by the pin members so as to control a degree of such waving.
On the other hand, the manufacturing method as disclosed in the above EP Patent No. 0228293 is accomplished under the same technological concept as the aforementioned U.S. patent so as to prevent occurrence of excessive waving as described above. This European Patent is different from the aforementioned U.S. patent in the following point. While the molten resin is introduced from a center of an opening of the eyelet toward an inner peripheral portion of the cavity according to the U.S. patent, according to the European Patent, it can be estimated that the molten resin is not introduced from a center of an engaging opening of a female fastening member into the cavity, considering that upper and lower dies for the engaging opening of the female member are in firm contact along their parting line, as shown in FIG. 4 showing a typical example of the EP Patent.
The invention according to Japanese Patent Application No. 10-138722 is based on a molding principle of the aforementioned US patent like the aforementioned European Patent, but further has been largely improved to make it possible that not only male/female fastening members of a snap fastener but also an eyelet and other fastening member are securely made integral with a tape. Further, the invention made it possible to dispose such different fastening members arbitrarily on the same tape, and further to provide a single kind of fastening members with various colors and the same fastening members and mold the fastening members of different materials.
According to the invention of this Japanese Patent Application No. 10-138722, firstly a base portion of synthetic resin having an opening at a center thereof is molded integrally on front and rear surfaces of a tape so as to enclose an entire peripheral portion of a mounting hole in a tape having at least one mounting hole. Next, an engaging portion is mounted integrally via an intermediate member of synthetic resin at least along an inner peripheral face of the opening of the base portion, or without such an intermediate member.
However, what should be most noticed of the invention Japanese Patent Application No. 10-138722 is that the base portion is constructed separately from the engaging portion via an intermediate member or without an intermediate member. Generally, when the base portion is molded integrally on a mounting-hole peripheral portion of the tape, appropriate waving generated in the mounting-hole peripheral portion of the tape is favorable because this improves a fixing strength between the tape and base portion, as described in the U.S. patent.
According to the invention of Japanese Patent Application No. 10-138722, the base portion is molded integrally directly on the tape by improving the aforementioned US patent method, and the engaging portion is molded integrally to the opening of the base portion molded on the tape or an opening of the intermediate member appropriately in a demanded form. The base portion can be molded freely without being restricted by a shape or material of the engaging portion as far as it has an opening. Therefore, a basic shape of the base portion can be commonly applied to diversified conFIGurations of the engaging portions. Thus, it is possible to manufacture a large number of tapes on which a number of base portions having the same conFIGurations are molded integrally, and then to integrally mount a necessary number of engaging portions having required shapes on the base portions at the same time or individually.
Meanwhile, this kind of fastener with tape, particularly the snap fastener, is demanded to have not only economic performance, but also its required characteristic, namely appropriate stiffness and elasticity. As material having such a characteristic, polyacetal resin is most suitable and therefore generally used, buts as a rare case, nylon or polybutylene terephthalate is used.
On the other hand, because it has become possible to effectively mold fastening members having various shapes and characteristics due to a progress of the molding technology, application field thereof has been expanding. Therefore, although the application of conventional fastener with tape was restricted to, for example, baby clothes or products not requiring heat treatment under high temperature after use such as under wears and bags, the application field thereof has been expanding to ordinary clothes, and further to other various fields.
Such expansion of the application field cannot be accomplished by only improvement of the molding technology, so there has occurred a problem particular to such application field. Particularly if this kind of the fastener is employed in ordinary clothes, large-step improvement of durability capable of bearing repeated use is demanded to the fastener, considering economic performance, and development of material capable of bearing heat treatment under high temperature is demanded.
Under such circumstance, polyacetal resin, which has appropriate stiffness and elasticity as an engaging/disengaging device, has been generally used. However, it has not met diversification of applications of the fasteners because its softening temperature is low and it is softened easily at about 170.degree. C. For example, when a fastener with tape made of polyacetal resin is affixed to ordinary clothes, this fastener is deformed easily by pressing with a household electronic iron, so that not only a function of the fastener is lost easily, but also an appearance thereof is damaged. Further, engaging/disengaging operation of the fastener of ordinary clothes is carried out more frequently than products conventionally provided with this kind of the fastener, and therefore the durability thereof needs to be increased by far more than it was.
If considering nylon or polybutyl terephthalate, which is seldom used as this kind of the fastener, its melting point thereof is high so that they can bear heat treatment by a household iron or the like, but they are not sufficiently useful as this kind of the fastener from the standpoints of elasticity and stiffness. The stiffness of polyacetal resin is 25,000 kg/cm.sup.2 or more and the elasticity thereof is 15,000-45,000 kg/cm.sup.2, however, values of nylon soaked with water are by far lower than those values.
Usually, in case of this kind of fastener, if its stiffness is too low, a fixing strength of the fastener integrally molded to the tape becomes weak so that in use, it is easily detached from the tape. If the elasticity thereof is low, engaging force between the male and female fastening members becomes weak so that they are easily disengaged from each other. On the other hand, considering wear resistance, portions of the male and female engaging portions, that is, a stud portion of the male portion and a socket portion of the female portion that are integrated with the tape, are desired to be made of homogeneous materials.
For example, in case of a snap fastener, if nylon is used for a male fastening member and polyacetal resin is used for the female fastening member, and if engaging/disengaging operation is repeated, a surface of the stud portion of the male fastening member is worn out in a relatively short time, so that its engaging/disengaging function is largely reduced. Therefore, generally, it is preferable to use synthetic resin of homogeneous material for the male and female fastening members in viewpoint of improvement of durability.